| 5 | k | + | 8 | ÷ | 5 | × | ( | 12 | − | 8 | k | ) | = | 15 |
| 方程左边 = | 5 | k | + | 8 5 | ( | 12 | − | 8 | k | ) |
| 5 | k | + | 8 5 | ( | 12 | − | 8 | k | ) | = | 15 |
| 方程左边 = | 5 | k | + | 8 5 | × | 12 | − | 8 5 | × | 8 | k |
| = | 5 | k | + | 96 5 | − | 64 5 | k |
| = | - | 39 5 | k | + | 96 5 |
| - | 39 5 | k | + | 96 5 | = | 15 |
| - | 39 5 | k | = | 15 | − | 96 5 |
| - | 39 5 | k | = | - | 21 5 |
21 5 | = | 39 5 | k |
39 5 | k | = | 21 5 |
| k | = | 21 5 | ÷ | 39 5 |
| = | 21 5 | × | 5 39 |
| = | 7 | × | 1 13 |
| k | = | 7 13 |
| k | = | 0.538462 |